Agent for the dispelling of fog and process for their preparation

ABSTRACT

Water-soluble condensation products of phenols and formaldehyde or compounds being capable of splitting off formaldehyde are useful as fog-dispelling agents.

United States Patent [191 Kiihne et al. 1 Feb. 6, 1973 AGENT FOR THE DISPELLING OF FOG AND PROCESS FOR THEIR [52] US. Cl ..252/319, 239/2 PREPARATION [51] Int. Cl. ..BOld 17/00 [58] Field of Search ..252/319; 239/2 [75] Inventors: Rudolf Kuhne, Frankfurt am Main;

Helmut Diery, Kelkheim, Taunus; [56] References Cited Siegbert Rittner, Frankfurt am Main, all of Germany UNITED STATES PATENTS [73] Assignee: Farbwerke Hoechst Aktien- 2,962,450 11/1960 Elod et a]. ..252/319 gesellschaft vormals Meister Lucius & Bruning, Frankfurt/Mai G Primary Examiner-John D. Welsh many Attorney-Curtis, Morris & Safford [22] Filed: April 6, 1971 [57] ABSTRACT [2]] App! 131306 Water-soluble condensation products of phenols and formaldehyde or compounds being capable of splitting 30 Foreign A li p i Data off formaldehyde are useful as fog-dispelling agents.

April 8, 1970 Germany ..P 20 16 705.9

14 Claims, No Drawings AGENT FOR THE DISPELLING OF FOG AND PROCESS FOR THEIR PREPARATION The present invention relates to a fog-dispelling agent consisting of a phenol-formaldehyde-resin. It is known that the autumn and winter months are an especially critical period for civil air traffic by the presence of fog. Despite a highly developed radiolocation system, it often occurs in the case of fog that airplanes which have been safely guided by radio beam to reach the proximity of the air strip, are forced to return and to head for the next fog-free airport, since the location beacons set at the beginning of the flight strip are not perceptible from'a 30 m altitude (standard value of landing category ll). Deviations to alternate airfields, delays, even cancelling of flights which cause great financial disadvantages to the concerned companies, normally result from the presence of fog. Apart from aviation, the removal of fog plays an important part, for example at crossings, docks and the like. Apart from these economic aspects, fog implies still other hazards.

Furthermore, it is known that different attempts have been started to develop processes and agents for removing fog from flight strips on airports; on principle the problem has been dealt with thermal, electrical, physical, mechanical and chemical methods. Thus the heating and removal of fog from fog-containing air have been performed by burning gasoline. Alternatively, efforts have been made to remove fog by means of electrically charged particles, electric fields, sound fields, dry ice, ice particles, cold water drops and hygroscopic substances such as CaCl or finely divided NaCl. A mechanical process using rotating sieves has also become known. However, none of these proposals could get a firm stand in practice. The thermal process of burning gasoline, tested especially in England during the last war, is much too expensive, as concerns fuel; the electrical and physical processes are extremely expensive with regard to their plant and operation costs; NaCl and CaCl, cause high corrosion. Dry ice has only a limited efficiency (in the case of under-cooled fogs), and the mechanical process using rotating sieves removes fog only in insufficient amounts. Finally, chemical methods have been employed, using chemical compounds such as silver iodide or tensides for fighting fog. However, silver-iodide is too expensive and efficient only for fighting undercooled fog. Tensides as described in German Pat. No. 956,278 and in US Pat. No. 2,962,450 (long-chained alkyl sulfates and alkyl sulfonates), have neither been suitable for solving the fog dispelling problem.

It has been found and it was surprising that watersoluble condensation products, containing sulfo groups, of phenol compounds and formaldehyde or substances yielding formaldehyde show a good efficiency in fog removing. The condensation products are preferably employed in a powdered form, especially with a particle size of from about 1 to 100 .4..

The condensation products are prepared from mononuclear phenols containing sulfo groups and/or binuclear condensed and/or non-condensed monoor bifunctional phenols containing sulfo groups and formaldehyde or substances yielding formaldehyde or from the corresponding phenols free from sulfo groups, formaldehyde or substances yielding formaldehyde and sulfites; the molar ratio of the phenol component to formaldehyde reaches from about 1:1 to 3.5. The con densation products to be used according to the invention may be prepared by reacting the phenol component with formaldehyde and alkali metal sulfite or alkali hydrogen-sultite in the alkaline range (for example according to Fiat Final Report 1013) or by reacting the phenol component, the nucleus of which is sulfonated, with formaldehyde (Houben-Weyl, Methoden der organischen Chemie, volume 14/2, page 264). instead of formaldehyde or substances yielding formaldehyde and alkali metal sulfite there may also be employed an alkali metal salt of the hydroxymethane-sulfonic acid.

As alkali metal sulfites there are especially considered the potassium, especially the sodium sulfites, the hydrogen-sulfites and disulfites.

As substances yielding formaldehyde there are used according to the invention formaline, paraformaldehyde, trioxan and formales, preferably those with low-molecular-weight alcohols, especially lower alkanols.

As suitable mono-nuclear phenols there may be mentioned for example phenol, o-cresol, m-cresol or technical cresol mixtures, halogeno-phenols such as ochloro-phenol, o-sec.-butylphenol, o-tert.-butyl-phenol and xylenols.

There are preferably used alkyl phenols, the alkyl groups of which have altogether less than four carbon atoms. The phenol components may be used in pure form, in technical mixtures or in the mixture of different individual components.

As example for the use of different phenols according to the invention there may be mentioned about 3 percent to about 30 percent by weight of phenols substituted by alkyl or aryl radicals, for example p-tert.-butylphenol, o-phenylphenol, l-phenyl-l-(hydroxyphenyl)-ethane (prepared from phenol and styrene) in mixture with for example cresols or chloro-phenols in the condensation mixture. lf polynuclear phenols are used it has to be taken care that the water-solubility of the condensation products is not affected. As binuclear, non-condensed phenols there may be mentioned for example 4,4'-dihydroxydiphenylmethane, 4,4- dihydroxydiphenylpropan, 4,4-dihydroxydiphenylsulfone, 2,2'- and 4,4'-dihydroxydiphenyl; the known precautions must be taken that the condensation does not lead to water-insoluble products.

As phenol compounds the nucleus of which is sulfonated there may be employed for example o-phenol' sulfonic acid, phenol-sulfonic acid mixtures, cresol sulfonic acids, B-naphtol-6-sulfonic acid and the like. The phenols the nuclei of which are sulfonated, may be condensed in pure form with formaldehyde or substances yielding formaldehyde or in mixture with the above phenols or in mixture with phenols, formaldehyde or substances yielding formaldehyde and alkali metal sulfites.

The condensation period may range between about 2 and about 15 hours; in general however, products of good efficiency are obtained, if the reaction time ranges between about 5 and about ll hours, at a temperature of from about C. to about l20C.

The anti-clogging agents to be used according to the invention are furthermore distinguished by the fact that they are non-corrosive to the metals and metal alloys used in vehicle and especially airplane construction.

1n the following, the preparation and the properties of the anti-clogging agents according to the invention and their use are explained in detailled manner. All parts and percentages are by weight unless otherwise stated, the ratio of parts by weight to parts by volume being the same as that of the kilogram to the liter. Condensation product 1 From cresol, 2-naphthol-6-sulfonic acid, formaldehyde and sodium sulfite, a pulverized phenol formaldehyde condensation product containing sulfo groups is obtained according to Fiat Final Report 1013; the particle size being about 10 to 20 u. Condensation product 2 A mixture consisting of 302 parts of a technicalgrade cresol fraction containing about 40 percent of mcresol, 16 parts of tripropylene-phenol (prepared from phenol and tripropylene), 528 parts of crystallized sodium sulfite and 500 parts of a 30 percent formaline in 300 parts of water was condensed for six hours at 102 105C. The whole was cooled to 80C, diluted with 645 parts of water, neutralized with sulfuric acid at room temperature and finally, the solution was converted into a fine powder by spray drying. The size of the particles used for fog removing was in the range of from about 1 to 100 t. Condensation product 3 120 Parts of a technical-grade cresol fraction (containing about 40 percent of m-cresol), 39 parts of 2,2- dihydroxydiphenyl, 264 parts of crystallized sodium sulfite and 200 parts of a 30 percent formaline in 155 parts of water were condensed for 11 hours at 102 105C. The product diluted after condensation with 100 parts of water at 80C and neutralized with sulfuric acid was spray-dried and used for fog removing in form ofa powder having a particle size of 10 20 u. Condensation product 4 200 Parts of water, 159 parts of m-cresol, 132 parts of sodium sulfite and 200 parts of a 30 percent formaldehyde solution were heated while stirring for 1 1 hours to 102-105C, then mixed at 70-80C with 186 parts of water, then neutralized at room temperature with sulfuric acid and the obtained condensation product was submitted to spray-drying. For fog-removing, the powder was used with a particle size of5 2011.. Condensation produce 5 A mixture consisting of 186 parts of water, 264 parts of crystallized sodium sulfite, 180 parts of technical xylenol mixture and 200 parts of a 30 percent formaline was stirred for 11 hours at 102 105C. The condensate diluted after the condensation with 100 parts of water at 80C and neutralized with sulfuric sulfuric acid was spray-dried and used for fog removing in form ofa powder having a particle size of -20 a. Condensation product 6 189 Parts of o-chlorophenol, 132 parts of sodium sulfite and 200 parts of a 30 percent formaldehyde solution were heated for condensation in 150 parts of water for 11 hours to a temperature of 102 105C. The whole was diluted at 80C with 282 parts of water and neutralized with sulfuric acid. The thus-prepared condensate was spray-dried, and the powder having a particle size of 10 30 p. was used for removing fog.

The dissemination of condensation product accordingto the invention, in the foggy space to remove fog may be varied within relatively wide limits of from about 1 mg/m to mg/m. It is comprehensive, however, that the effectively required amount has to found, as the case may be, on the basis of meteorological parameters, for example wind speed.

In order to perform the process according to the invention, different equipments may be used. For example one or several helicopters or small airplanes may be employed for spraying the condensation product according to the invention into the fog; alternatively, the articles may be introduced or shot into the fog, from the ground, for example with large-sized ventilators or blast apparatuses. Furthermore, pressurized gases such as compressed air, CO N or fluorinated hydrocarbons may also serve as propellant for the compounds according to the invention.

EXAMPLE 1 in a steel chamber of 600 in capacity, a fog was produced at 20C according to the principle of adiabatic expansion having the following parameters:

Average drop radius 4 5 u Range of drop radius 2 22 1. Concentration of liquid 200 mg/m water Concentration of drops 350/cm horizontal visibility 60 m 5 grams of the condensation product 1 were sprayed through an inlet in the copula of the chamber. After a few minutes already, a sudden thinning of the fog could be observed. The horizontal modification of visibility in the chamber determined by means of transmissometers (according to the principle of clouding measuring) and graphically registrated, showed after only 15 minutes an about fivefold improved visibility. A non-treated fog (blanc test) produced with the same apparatuses remained practically unchanged during this period.

EXAMPLE 2 5 g of the condensation product 2 were introduce for fog removing into the same steel chamber as described in Example 1 under the same working conditions. Similar to Example 1, a sudden thinning of the fog was observed, and after 15 minutes a 3.5 times improved visibility was obtained.

EXAMPLE 3 5 g of the condensation product 3 were introduced into a natural fog, in which marked sticks were installed, the visibility being 3 m (density of fog 2 3 g/m) and the temperature being 10C, from a 10 m altitude by means of a steel cylinder which contained the pulverized condensation product 3 and was pressurized with CO, as propellant. Within 10 minutes, the visibility in the fog was improved to 12 m. No visibility improvement was observed during the blank test, where the fog was treated only with the finely sprayed CO EXAMPLE 4 In a natural fog of the same composition and measuring apparatus as described in Example 3, the condensation products 4, 5 and 6 were tested under the same conditions (steel cylinder with CO as propellant). The visibility was improved from 3 to 14 m by the condensation product 4, from 3 to 12 m by the condensation product 5 and also from 3 to 12 m by the condensation product 6. ln blank tests carried out in analogy to Example 3 visibility did not improve.

We claim:

1. A process for dispelling fog which comprises contacting the fog with a water-soluble condensation product prepared a. by reaction of mononuclear phenol containing sulfo groups and/or binuclear condensed and/or non-condensed, mono or bifun'ctional phenol containing sulfo groups with formaldehyde or in formaline or with paraformaldehyde, trioxan or formales, or

b. by reaction of the above-mentioned corresponding phenols free from sulfo groups with formaldehyde or in formaline or with paraformaldehyde, trioxan or formales, and with alkali metal sulfite or alkali hydrogen sulfite in the alkaline range, or

c. by the reaction of alkali metal salts of the hydroxy methane sulfonic acids with the corresponding above-mentioned phenols, wherein the molar ratio of the phenol component to formaldehyde is about 1:1 to about 1:3.5.

2. The process defined in claim 1 wherein the condensation product consists essentially of a condensation product obtained by alkaline condensation of a. a monocyclic phenol free of sulfo groups,

b. formaldehyde, formaline, paraformaldehyde,

trioxan or formal, and

c. an alkali metal sulfite.

3. The process defined in claim 1 wherein the condensation product consists essentially of a condensation product of a. a monocyclic lower-alkyl-phenol having no sulfo groups,

b. formaldehyde, formaline,

trioxan or a formal, and

c. an alkali metal sulfite.

4. The process defined in claim 1 wherein the condensation product consists essentially of a mixed condensation product of a. a phenol mixture of 3 to 30 percent by weight of a condensed or uncondensed bicyclic phenol and 97 to 70 percent by weight ofa monocyclic phenol,

b. formaldehyde, formaline, paraformaldehyde,

trioxan or a formal, and

c. an alkali metal sulfite.

paraformaldehyde,

5. The process defined in claim 1 wherein the condensation product is sprayed into the fog in the form of a powder having a particle size of about 1 to u.

6. The process defined in claim 1 wherein the condensation product is sprayed into the fog in the form of a powder having a particle size of about 5 to about 30 7. The process defined in claim 1 wherein about 1 to about 100 mg/m of the condensation product having a particle size of about 5 to about 30 u are sprayed into the fog.

8. A process for dispelling fog which comprises spraying into the fog an effective amount of a water- 'soluble powder having a particle'size of about 1 to about 100 t, said powder being a condensation product of a. a monoor binuclear, sulfonated phenol with formaldehyde, formaline, paraformaldehyde, trioxan or formal; b. a monoor binuclear unsulfonated phenol with formaldehyde, formaline, paraformaldehyde, trioxan or formal and with an alkali metal sulfite or an alkali metal hydrogen sulfite, or

c. a monoor binuclear phenol with an alkali metal salt of hydroxymethane sulfonic acid, said condensation product having a molar ratio of phenol component to formaldehyde in the range of about 1:1 to 1:3.5.

9. The process defined in claim 8 wherein the powder is a condensation product of cresol, 2- naphthol-6-sulfonic acid, formaldehyde and sodium sulfite.

10. The process defined in claim 8 wherein the powder is a condensation product of cresol, tripropylenephenol, sodium sulfite and formaline.

11. The process defined in claim 8 wherein the powder is a condensation product of cresol, 2,2- dihydroxydiphenyl, sodium sulfite and formaline.

12. The process defined in claim 8 wherein the powder is a condensation product of cresol, sodium sulfite and formaldehyde.

13. The process defined in claim 8 wherein the powder is a condensation product of sodium sulfite, xylenol and formaline.

14. The process defined in claim 8 wherein the powder is a condensation product of borthochlorophenol, sodium sulfite and formaldehyde. 

1. A process for dispelling fog which comprises contacting the fog with a water-soluble condensation product prepared a. by reaction of mononuclear phenol containing sulfo groups and/or binuclear condensed and/or non-condensed, mono- or bifunctional phenol containing sulfo groups with formaldehyde or in formaline or with paraformaldehyde, trioxan or formales, or b. by reaction of the above-mentioned corresponding phenols free from sulfo groups with formaldehyde or in formaline or with paraformaldehyde, trioxan or formales, and with alkali metal sulfite or alkali hydrogen sulfite in the alkaline range, or c. by the reaction of alkali metal salts of the hydroxy methane sulfonic acids with the corresponding above-mentioned phenols, wherein the molar ratio of the phenol component to formaldehyde is about 1:1 to about 1:3.5.
 2. The process defined in claim 1 wherein the condensation product consists essentially of a condensation product obtained by alkaline condensation of a. a monocyclic phenol free of sulfo groups, b. formaldehyde, formaline, paraformaldehyde, trioxan or formal, and c. an alkali metal sulfite.
 3. The process defined in claim 1 wherein the condensation product Consists essentially of a condensation product of a. a monocyclic lower-alkyl-phenol having no sulfo groups, b. formaldehyde, formaline, paraformaldehyde, trioxan or a formal, and c. an alkali metal sulfite.
 4. The process defined in claim 1 wherein the condensation product consists essentially of a mixed condensation product of a. a phenol mixture of 3 to 30 percent by weight of a condensed or uncondensed bicyclic phenol and 97 to 70 percent by weight of a monocyclic phenol, b. formaldehyde, formaline, paraformaldehyde, trioxan or a formal, and c. an alkali metal sulfite.
 5. The process defined in claim 1 wherein the condensation product is sprayed into the fog in the form of a powder having a particle size of about 1 to 100 Mu .
 6. The process defined in claim 1 wherein the condensation product is sprayed into the fog in the form of a powder having a particle size of about 5 to about 30 Mu .
 7. The process defined in claim 1 wherein about 1 to about 100 mg/m3 of the condensation product having a particle size of about 5 to about 30 Mu are sprayed into the fog.
 8. A process for dispelling fog which comprises spraying into the fog an effective amount of a water-soluble powder having a particle size of about 1 to about 100 Mu , said powder being a condensation product of a. a mono- or binuclear, sulfonated phenol with formaldehyde, formaline, paraformaldehyde, trioxan or formal; b. a mono- or binuclear unsulfonated phenol with formaldehyde, formaline, paraformaldehyde, trioxan or formal and with an alkali metal sulfite or an alkali metal hydrogen sulfite, or c. a mono- or binuclear phenol with an alkali metal salt of hydroxymethane sulfonic acid, said condensation product having a molar ratio of phenol component to formaldehyde in the range of about 1:1 to 1:3.5.
 9. The process defined in claim 8 wherein the powder is a condensation product of cresol, 2-naphthol-6-sulfonic acid, formaldehyde and sodium sulfite.
 10. The process defined in claim 8 wherein the powder is a condensation product of cresol, tripropylenephenol, sodium sulfite and formaline.
 11. The process defined in claim 8 wherein the powder is a condensation product of cresol, 2,2''-dihydroxydiphenyl, sodium sulfite and formaline.
 12. The process defined in claim 8 wherein the powder is a condensation product of cresol, sodium sulfite and formaldehyde.
 13. The process defined in claim 8 wherein the powder is a condensation product of sodium sulfite, xylenol and formaline. 